Zoom ADSL modems will only sync if the DSL service is on the center 2 pins of the phone wire (red-green wires).
A standard phone wall Jack and Phone Line has 4 wires. Usually a single line or Line 1 will use the center 2 wires (red-green pair), and Line 2 will use the outside pair (black-yellow pair). If your original ADSL modem works fine but the new Zoom modem will NOT SYNC, this may be because of one of the following reasons;
The previous ADSL modem that you had (eg. ALCATEL 1000 and Others), has connectors that are wired to work on the outside pair and used a specially wired cable that came with that modem
The ADSL service is actually provided over Line 2 (outside wires).
If you are not sure whether your ADSL service is actually on Line 2, and the Zoom ADSL modem will not sync, but your old modem works fine, make sure you swap out the phone cable that came with your old modem and use the new phone cable that came with the Zoom ADSL modem. Again, this is in case the original phone cable was specially wired as for the ALCATEL 1000 which rewired the inside wires to be swapped to the outside in order to sync up properly.
If you know that the ADSL service is on line 2, or if swapping out phone cables did not work, then you have the following options:
- You can get a line 1 line 2 "T" adaptor (Radio Shack) and plug the Zoom modem into line 2.
- There are also "line swapper" devices that will swap line 1 and line 2.
- You might be able to re-wire the jack by putting the black -yellow pair of wires onto the Red Green pair.